Does anyone know this result?

Does anyone know this result?

Let $A$ be a matrix symmetric matrix such that $\lambda I \le A(x) \le \Lambda I$ where $I$ is the identity and $v$ is a solution of $\mbox{div}(A(x)\nabla v) = 0$ in $B_R \subset \mathbb{R^{n}}$. Then for some constant $0<\alpha<1$ we have $$\int_{B_r} | \nabla v - (\nabla v)_r|^{2}dx \le C(\lambda, \Lambda)\Bigl( \dfrac{r}{R}\Bigr)^{n - 2 + 2\alpha} \int_{B_r}| \nabla v(x) -(\nabla v)_{R}|^{2}dx$$ for any $0<r<R$.Where $(f)_{r}$ is the classical average notation $$(f)_{r} = \dfrac{1}{|B_r|}\int_{B_r}f dx.$$

If you know this result or result similar, or you know some reference for this, please tell me.

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What is $(\nabla v)_r$? – Dirk Jun 14 '12 at 17:40
I wrote above now. – user29999 Jun 14 '12 at 17:57